A number of implantable blood pumps are in use or under development for application as either artificial hearts or cardiac assist devices. Some of the blood pumps circulate blood based on rotary flow. A centrifugal flow pump, for example, causes blood to circulate by the turning of an impeller mechanism mounted on an axis in a blood flow chamber in which the axis is perpendicular to the direction of the blood flow. Another example of a blood pump is the axial flow pump, which causes blood to circulate by the turning of an impeller mechanism mounted within a blood flow chamber. The impeller mechanism rotates around an axis that runs in the direction of the blood flow. Both of these pumps may be implemented using a bearing system to maintain the position of the impeller mechanism. They also may be implemented using a magnetically levitated (i.e., bearingless) impeller mechanism mounted within a blood flow chamber.
The interior surface of the pump may be smooth or textured. A smooth surface is intended to prevent growth of a biologic lining of protein and cells, and may be used on moving parts in which a biologic lining is unlikely to form. Textured surfaces, on the other hand, are intended to prevent thromboembolic complications by promoting a biologic lining that adheres to the textured surface. A textured surface may be used on a stationary surface of a blood pump or on another surface not subject to high centrifugal or other forces that hinder or prevent adherence and growth of the lining.